✔ 最佳答案
Note that P(Tom wins a game) = 1 - 0.6 = 0.4
1)P( Joe wins the match)= P(End with 4 games and Joe wins the last game)
+ P(End with 5 games and Joe wins the last game)
+ P(End with 6 games and Joe wins the last game)
+ P(End with 7 games and Joe wins the last game)= 0.6^4
+ (4C3)(0.6^3)(0.4) (0.6)
+ (5C3)(0.6^3)(0.4^2) (0.6)
+ (6C3)(0.6^3)(0.4^3) (0.6)= 0.1296
+ 0.20736
+ 0.20736
+ 0.165888= 0.710208= 11097/15625
2)P(Joe wins the match and Tom has won 2 games)= 0.20736 / 0.710208= 0.291970803= 40/137
2010-12-23 19:53:47 補充:
P(Joe wins the match and Tom has won 2 games)
= P(End with 6 games and Joe wins the last game) / P( Joe wins the match)